[ 40 years of 5-fluorouracil--still an attractive cytostatic]

On its 40th birthday 5-fluorouracil (FU) is still an attractive drug frequently employed in adjuvant and palliative treatment of colorectal and breast cancer, head and neck cancer, oesophageal cancer and anal cancer. After all this time it is still not known what the optimal schedule or the best form of administration is, and whether or not modulation of the drug is of any benefit. This article deals with the drug's different modes of action depending on the schedule of administration. An overview of the literature on drug modulation is given. We introduce the less well-known side effects of the drug and the newly developed orally administered prodrugs of FU.